ABSTRACT/ PROJECT SUMMARY Pain is one of the top symptoms producing the greatest negative impact on cancer patients' quality of life. Unfortunately, one in three cancer patients will experience moderate to severe pain due to consequences of cancer, its treatments or both. For one in three, pain will persist after completion of active cancer treatments. With 15.5 million Americans living with cancer, this is a substantial public health matter. While many complementary and alternative medicine approaches exist, their clinical use for cancer pain remains seriously hampered by lack of robust evidence, short-term relief, and excessive out-of-pocket costs. In turn, opioid pain medications are prescribed to cancer patients ? who notably, also remain excluded from most state and policy initiatives on opioids. Long-term (>3 months ) opioid therapy is also prevalent among cancer outpatients when compared to age-sex matched controls. Despite this, cancer patients have been almost invariably excluded from T he recent Health management? studies investigating the outcomes of long-term opioid therapy and use. and Human Services Pain Management Inter-Agency Taskforce has identified ?self- as one of the best practices in improving chronic pain. However,interventions cannot be designed due to serious gaps in our current understanding of cancer outpatients' pain self-management and especially their opioid self-management. Recent systematic reviews demonstrate that most cancer pain interventions (based on knowledge translation and conducted predominantly or exclusively with White patients) improve knowledge, but largely do not improve outcomes that matter to patients such as daily pain, function, or quality of life. This underscores a need to continue in search of other targets for intervention development. This 6-month prospective cohort study will generate new knowledge about longitudinal pain, opioid self- management trajectories, and associated outcomes among cancer outpatients in the context of daily pain, pain flares, key clinical moderators and covariates. A total of 400 cancer outpatients (50% African Americans; 50% women) who are prescribed long-acting (LA) opioids will be recruited from three urban oncology centers. Longitudinal opioid self-management patterns will be captured in real-time using medication event monitoring system (MEMS). Daily background pain, pain flares, and use of ?as-needed? opioids will be collected using the self-report tracker (SRT). Patient-reported outcomes (PRO) to be assessed are changes in pain levels, function, sleep, and health-related quality of life. Health services outcomes include unplanned hospitalizations and emergency department use (healthcare utilization). This study will supply rigorous data, comprehensive set of sociodemographic and clinical covariates, and key moderators upon which further research for pain-self management best practices can be based, including targets to ameliorate racial disparities. Overall, this research can have a sustained impact on the science of cancer pain management.